April 2012 Archives

One quirk of working for Physics World is that most staff members are assigned a British newspaper to skim each day in search of science news. The exact rationale determining which of us gets what paper is not entirely clear, but for whatever reason, I have ended up with that venerable mouthpiece of British conservatism, the Daily Telegraph.

As a result of this arrangement, I have become a connoisseur (if that’s not too flippant a word) of the Telegraph’s obituaries page. My favourites are the obituaries of eccentric aristocrats straight out of P G Wodehouse, but the Telegraph’s writers also have a nice line in honouring little-known heroes of World War II – and every now and then, I come across an obituary with a connection to physics.

Take yesterday’s entry on Sydney Wignall, an adventurer and marine archaeologist who died on 6 April at the age of 89. Wignall was best known for leading a 1955 expedition to the Tibetan Himalayas that ended with his capture and torture by Chinese troops, who suspected him (accurately, as it turned out) of being a spy. Later in life, however, he was instrumental in excavating two wrecked ships from the ill-fated Spanish Armada. In the course of this project, Wignall discovered that an inadequate understanding of materials science probably contributed to the Armada’s defeat.

To understand how, you first need to appreciate that when the Armada sailed in 1588, marine gunnery was still in its infancy. In fact, a proper science of ballistics would not appear until 150 years later, when a British military engineer, Benjamin Robins, began a systematic study of cannon-ball trajectories using Newtonian mechanics. To make matters worse, the stone, lead and iron shot available to 16th century gunners were anything but uniform. This non-uniformity meant that a cannon loaded in the same way, with the same amount of gunpowder (another notoriously non-uniform quantity), by the same people, elevated to the same angle and fired at the same point in the ship’s rolling motion would almost certainly not deliver its deadly package to the same place.

Wignall’s contribution was to show that Spanish gunners faced an extra difficulty. By performing X-ray analyses on shot brought up from wrecks on the sea floor, Wignall’s team was able to demonstrate that Spanish craftsmen had routinely poured cold water into the moulds after the shot was cast. This sped up the manufacturing process, but it also caused the outer layers of the shot to contract and become brittle. In addition, the archaeologists found that some of the Spanish 7-inch-diameter iron shot was partly composed of recycled 3-inch shot. These smaller metal spheres would melt only imperfectly during casting, which meant that the final product had a very non-uniform density and was unstable in flight.

It is probably for historians, not physicists or materials scientists, to determine how much this poorly made Spanish shot contributed to the Armada’s defeat. But it is pretty clear that it would have been, as a minimum, a source of immense frustration for the Spanish gun crews, who repeatedly watched their perfectly aimed shots veer away from their targets for no apparent reason – all for the want of better metallurgy.

Today is being heralded as the 50th anniversary of the UK in space. That is because on 26 April 1962 the Ariel 1 satellite was launched, marking the nation’s first step into the final frontier and making it the world’s third space-faring nation. The Ariel 1 mission also signified the world’s first international space mission – while the mission carried six scientific experiments designed and built by UK space scientists, the satellite itself was built and launched on US soil, by NASA.

This bilateral mission may come as a surprise, because the space race of the 1960s is usually seen as a two-horse affair between the US and the USSR. The collaboration between the UK and the US resulted from the Eisenhower administration’s 1959 offer to launch allies’ space-science instruments, free of charge, on US rockets.

Of course, it was indeed the two superpowers, acting unilaterally, that reached the two most significant milestones of the space race. The Soviets had stunned the Americans when Yuri Gagarin became the first person in space in 1961. But a generation of US national investment paid off when Neil Armstrong took that first small step on the Moon in 1969.

Today, space exploration is no longer the domain of just two superpowers. Many other nations have space programmes, and satellites have been launched by more than 50 nations – everyone from Italy to Israel, via Morocco and Mauritius. The space industry has also matured, with the majority of space missions now take place for strategic or commercial purposes, such as launching global positioning satellites and instruments to collect environmental data. Space missions are also no longer carried out exclusively by national agencies; an increasing number of private enterprises are starting to invest in the space industry.

Looking to the long-term future of space exploration, there have been murmurings of a return to the Moon or even a manned mission to Mars, linked with both NASA and the China National Space Administration (CNSA). But many commentators have noted that without the “simplicity” of the political situation in the 1960s, it will be hard to generate the incentive to pour vast amounts of national money into expensive manned missions. And given the ongoing global financial crisis, the prospects for state-sponsored manned missions to space is unlikely to improve any time soon.

But those with a Promethean view of the space industry will be confident that humans will one day resume manned exploration of space. And when we do, who will be in the driving seat? In this week’s Facebook poll, we want you to let us know how you think this quest will continue.

Which of these is most likely to reach the next significant milestone in manned space exploration?

The USRussiaAn emerging space nation such as China or IndiaAn international collaborationA private company

Have your say by casting your vote on our Facebook page. And feel free to post a comment to explain your choice or to make an alternative suggestion. You can also read how US astrophysicist and science popularizer Neil deGrasse Tyson makes the case for space exploration in this recent interview with physicsworld.com.

In last week’s poll, we looked at a topic close to the hearts of many condensed-matter physicists. We asked you to select your favourite quasiparticle from a list of five. The most popular, picking up 48% of the vote, was the phonon. Others opted for the hole (19%), the spinon (14%), the exciton (13%) and the wrinklon (7%).

Given its amusing name, several people actually questioned whether the wrinklon is a real particle, including Facebook user Heather Williams, who legitimately asked “Is there really such a thing as a wrinklon? It sounds like some nonsene they’d put on anti-aging cream.” But despite its name, I can confirm that the wrinklon does exist, at least according to these physicists, who described the new quasiparticle in a paper published last June in Physical Review Letters.

Thank you for all your participation and we look forward to hearing from you in this week’s poll.

Two snub hexagonal tilings that were generated in a 2D simulation of point particles interacting via an isotropic potential. The patterns are chiral and are mirror images (plus a rotation) of each other. (Courtesy: APS)

By Hamish Johnston

The chirality – or handedness – of many biological molecules plays an important role in their function. The amino acids that make up proteins only exist in the left-handed form, for example, while the sugars found in DNA are exclusively right-handed.

Why nature seems to favour one handedness over another has long puzzled physicists – particularly because the relevant physical laws that govern the synthesis of such molecules are symmetric and should not be biased towards right- or left-handedness.

The emergence of molecules with a specific chirality in a chemical process is usually understood in terms of chiral-specific catalysis, which accelerates the production of molecules of one handedness over the other. However, it’s also possible that chirality can emerge in much simpler systems that don’t involve complicated chemical reactions.

In order to understand how chirality emerges from symmetrical interactions, Martin Nilsson Jacobi and colleagues at Chalmers University in Sweden have done computer simulations that reveal how point particles acting under a spherically symmetric force can form chiral patterns in 2D. According to the team, the system begins with “maximal a priori symmetry” and therefore the emergence of asymmetric chiral patterns is surprising.

The team began with what it describes as the simplest form of chiral lattice in 2D. This is made from identical scalene triangles – a triangle with no sides of equal length. Such a lattice can be made in two ways, each being a mirror image of the other. However, one lattice cannot be transformed into the other by rotation or translation.

Nilsson Jacobi and colleagues first calculated the Fourier transform of the lattice, which gives its reciprocal lattice. Then, using a technique introduced by the team last year, they were able calculate a potential energy between pairs of lattice points that would result in the creation of the desired chiral lattice. The amazing thing about this potential is that it is spherically symmetric – looking a bit like a 1/r potential with a number of wiggles in it.

To confirm that the potential would indeed result in a chiral structure, the team then used a Monte Carlo simulation to determine what lattice would form if point particles were subject to such a potential. The resulting lattice was indeed a chiral pattern of scalene triangles.

The team then set its sights on a more complicated – and visually appealing – 2D chiral lattice called “snub hexagonal tiling” (see images above). Again, the chiral pattern emerged from the simulation.

While the team has shown that in principle chiral patterns can emerge from simple symmetric systems, this could prove to be very difficult to achieve in a real system. The problem is that the required potentials would be very difficult to recreate in a real-life system and “are not likely to appear in the near future,” according to the physicists.

The simulations are described in this paper in Physical Review Letters.

Since the birth of medicine 5000 years ago, physics has played a fundamental role in the development of health technologies. Significant contributions to today’s medical methods range from the application of numerous imaging techniques to diagnosis and patient screening, to the wide variety of treatment techniques made possible by the discovery of radiation and radioactivity.

For their part, medical physicists have a particularly important role to play, both in the discovery of new diagnostic and treatment techniques, and in ensuring the safe and effective implementation of new physics-based medical applications.

In recognition of these facts, the medical journal The Lancet has just published its Physics and Medicine Series, a set of five articles and two comments that highlight the many ways in which physics has revolutionized medical practice. The series, published to coincide with the anniversary of Albert Einstein’s death, calls for medical physics to be promoted as a career choice and recognized as a vocational discipline.

Writing in one of the associated comment articles, Peter Knight (right), president of the Institute of Physics – which publishes physicsworld.com – discusses the “long and happy marriage between physics and medicine”, and puts forward two proposals to keep this relationship thriving in the future.

First is the continued need to support and invest in the physical sciences. Knight notes that most, if not all, of the physics-based techniques and technologies described in the series derive from the discoveries of basic physics research that was undertaken purely to investigate the nature of our world and expand the frontiers of knowledge.

For example, the understanding and manipulation of radiation was made possible by basic research into the structure and evolution of the universe and the building blocks of matter. Knight urges the UK government and other funders to recognize that continued support for that research will deliver corresponding advances in medical technologies in the years to come.

Second, for medical practitioners to fully exploit modern physics-based technologies, it would be hugely beneficial for them to have a sound understanding of the physics involved. As such, Knight suggests that medical schools should consider restoring the requirement for applicants to hold physics-oriented qualifications for entry into medicine.

Another recommendation arising from the series is for closer collaboration and integration between the physical and life sciences, via a new model in which multidisciplinary teams work closely in a shared research environment. Finally, there is a need for every school to aspire to provide high-quality physics education, to ensure a supply of talented scientists who can perform health-related physics research in the future.

“The Lancet’s Physics and Medicine Series clearly shows the potential to diagnose and treat increasing numbers of patients, with increasing effectiveness, using physics-based techniques,” Knight concluded. “Understanding the physics that underpins these techniques would be a real advantage to medical practitioners, and to their patients.”

From Darwin and his tree of life to Mendeleev and his conception of a periodic table of elements, images and visual metaphors have played a vital role throughout the history of science. Today, the Royal Society has launched a new online picture library to allow people to browse and search its vast collection of images online for the first time. The collection includes paintings, drawings and prints dating back to when the society was founded in the mid-17th century. Here is a selection of the images connected with physics and physicists.

Orrery demonstrating the transit of Venus

This is a mechanical device known as an orrery, designed to show the relative positions and motions of the planets and moons in the solar system. The British instrument maker Benjamin Cole (1695–1766) made this orrery, which is of particular interest this year because it depicts a transit of Venus – a phenomenon that will occur in June for the last time for more than 100 years.

Eyes and head of a grey drone-fly

Flies can be a bit of a nuisance when buzzing around your head, but when viewed under a microscope, these insects are nothing short of hideous. This sketch of the eyes and head of a grey drone-fly was produced by the natural philosopher Robert Hooke and it appeared in the Royal Society’s 1665 publication Micrographia.

The waterwheel and conduit for Scrooby Mill

The Royal Society’s collection also contains a number of engineering and architectural plans, including this design for the waterwheel and conduit for Scrooby Mill in the English county of Nottinghamshire. It was sketched in 1782 by the British civil engineer John Smeaton.

Engraving of a flying fish

Finally, we have this image of a flying fish, which, according to the Royal Society, holds an unlikely place in the history of modern physics. It is part of a set of engravings from a 1686 book Historia Piscium (a History of Fishes) by John Ray and Francis Willughby, for which the Royal Society held high hopes. But after the society had invested all of its available funds, the book went on to be a flop, meaning there was no money left to publish Newton’s Philosophiæ Naturalis Principia Mathematica (Mathematical Principles of Natural Philosophy), which had been “knocking around the office”.

The story goes that a young Edmund Halley – then clerk at the Royal Society – saw the promise in Newton’s work and managed to raise the funds to publish the Principia, providing much of the money from his own pocket. Newton’s book was finally published in 1687, and went on to revolutionize our understanding of the physical world.

This week, an international group of researchers has hit the headlines by reporting the first-ever observation of a quasiparticle called the “orbiton”. First predicted a decade ago, the orbiton can be thought of as an electron in which the properties of spin and charge have been suppressed. Elsewhere in the news this week, a separate team has spotted a quasiparticle that resembles the elusive Majorana fermion predicted in the 1930s by Italian physicist Ettore Majorana.

Quasiparticles can be thought of as excitations in a solid that behave like tiny particles that obey quantum mechanics; a phonon, for example, is a quantized sound wave that propagates through a crystal.

However, the definition of a quasiparticle is not something that is universally accepted – indeed, some argue that a phonon is not a quasiparticle, by virtue of it being a boson rather than a fermion. Others ask whether these “particles” are in fact real physical entities or whether they are merely useful mathematical concepts for understanding the collective behaviour of real particles within bulk materials.

However you want to think about them, quasiparticles have proved themselves to be very useful. For instance, an entire fleet of electronic devices has been developed over the years thanks to our understanding of “holes”, which are quasiparticles representing the absence of an electron.

In this week’s Facebook poll, we want to know if you hold a particular affinity for any of these quasiparticles.

What is your favourite quasiparticle?

PhononSpinonHoleExcitonWrinklon

Have your say by casting your vote on our Facebook page. And feel free to post a comment to explain your choice or to nominate another quasiparticle not on our list.

In last week’s poll, we entered the realm of quantum mechanics, and we received a fantastic response to the question “What is the trickiest feature of quantum mechanics to get your head round?”. The results were as follows.

In addition to the votes, there was also a lively discussion on our Facebook page as people shared their experiences of grappling with the ideas of quantum mechanics. One user who goes by the name of Art Hobson wrote “A close look at wave–particle duality reveals that quantum physics is about fields, not particles. The so-called particles are simply excitations (waves) in these fields.”

Another Facebook user, Wendl Thomis, revealed that the feature of quantum mechanics he has most trouble with is the idea of virtual particles. “Virtual particles are postulated to come into and out of existence at every point of space at dizzying rates so that the energy there can fluctuate as quantum mechanics demands. A very non-intuitive idea,” he says.

Thank you for all your participation and we look forward to hearing from you in this week’s poll.

And if you want to learn more about the ideas of quantum mechanics, take a listen to the latest edition in the Physics World books podcast series, in which we discuss the enduring popularity of quantum mechanics in popular-science writing.

Stringed Relief, reproduced by permission of The Henry Moore Foundation

By James Dacey

My first experience of Henry Moore’s sculptures came from several visits to the Yorkshire Sculpture Park, located near where I grew up in the north of England. As a kid on a day trip with my parents, I was no art critic. But I was always fascinated by Moore’s looming bronze figures dotted across the rolling Yorkshire hillside. Within the works, I could see both the abstract body parts of a giant metal person, but also what appeared to be stark geometric shapes.

So, I was interested to hear the news that a new exhibition in London is celebrating Moore’s fascination with mathematics. The exhibition is being held jointly by the Royal Society and the Science Museum, and it showcases some of Moore’s lesser-known sculptures that were directly inspired by maths, including the work above, Stringed Relief. According to the exhibition catalogue, Moore (1898–1986) stated on several occasions that the use of string in his sculpture, which he started in 1937, was influenced by seeing models at the Science Museum in London.

I was fascinated by the mathematical models I saw there, which had been made to illustrate the difference of the form that is halfway between a square and a circle. One model had a square at one end with 20 holes along each side…Through these holes rings were threaded and lead to a circle with the same number of holes at the other end. A plane interposed through the middle shows the form that is halfway between a square and a circle…It wasn’t the scientific study of these models but the ability to look through the strings as with a bird cage and see one form within the other which excited me.

Moore is by no means the only artist to have drawn inspiration from the ideas of science. One high-profile contemporary example is the British artist Anthony Gormley, who has created several sculptures inspired by the theory of quantum mechanics. It has also been suggested that Picasso’s development of the Cubist style of painting was informed by a similar line of thinking to Einstein’s during the formulation of the theory of relativity.

In the latest episode of the Physics World books podcast, released yesterday, we look at the enduring appeal of quantum mechanics in popular-science books. I presented the programme along with Physics World’s editor Matin Durrani and the magazine’s reviews editor Margaret Harris, and we were joined by several authors of these books. In the podcast we explore the question of why it is that so many popular-science books have been written on the topic over the years, and why the public has such a strong fascination with the ideas of quantum physics. You can find more details and listen to the podcast here.

One of the aspects we discuss is the counterintuitive nature of the quantum world. On the one hand, this weirdness of quantum mechanics can be intriguing because it describes a world that is so different from our everyday experiences. But on the other hand, some of the concepts and the mathematics of quantum mechanics can be quite mind-boggling, and it can be difficult to explain these ideas in basic terms. I know from the experience of writing news articles about quantum mechanics that it can sometimes be very challenging to find everyday analogies to describe the quantum world while remaining faithful to the underlying physics.

But I want to know what you think about this, via this week’s Facebook poll question:

What is the trickiest feature of quantum mechanics to get your head round?

In last week’s poll we embraced Stephen Hawking-mania. The 70-year-old theoretical physicist appeared in an episode of the hit TV show The Big Bang Theory, which aired on CBS in the US last Thursday. Unfortunately, I haven’t been able to see the show yet here in the UK, but I have seen Hawking in some of his earlier cameos, including his several appearances in The Simpsons and his role in Star Trek: The Next Generation. We asked you “In which TV show should Stephen Hawking make his next cameo appearance?”.

The most popular choice by a country mile was Doctor Who, which picked up 70% of the votes. In second place with 18% of the vote was the slightly more leftfield choice that Hawking should appear in the US sitcom How I Met Your Mother. Just 7% of voters opted for the musical comedy-drama Glee, while only 4% opted for the cult UK sci-fi comedy Red Dwarf.

So, Stephen Hawking; producers of Doctor Who. Make this happen. For the sake of our Facebook fans, please.

Thank you for all your participation and we look forward to hearing from you in this week’s poll.

Thank you to everyone who took part in our last Physics World photo challenge. We asked readers to submit photos to our Flickr group relating to the theme of “portrait of our planet”. We had some great submissions, a selection of which are showcased in this article.

The theme for our new photo challenge is “doing physics”. We want you to submit your pictures of the process of science. It could be you or your colleagues working on an experiment in the laboratory, or perhaps out in the field collecting data, or maybe looking at the heavens through a telescope. Or perhaps you are more theoretically minded and you want to send us an image of your paper-littered office, or the chalkboard detailing the calculation that has been keeping you awake for the past two weeks. Be as creative as you like.

Please add your photos by Tuesday 8 May and then after this date we will choose a selection of our favourite images to be showcased on physicsworld.com. And feel free to write a caption to share the story behind the image. We look forward to your submissions.

Later today, fans of the hit comedy series The Big Bang Theory are in for a real treat, because the show includes a special guest appearance from Stephen Hawking. The 70-year-old theoretical physicist will be playing himself in an episode called “The Hawking Excitation”, which will be aired at 1900 (CST) on the CBS television channel. Details of the plotline are scarce, but this picture released by the CBS network shows the programme’s chief protagonist (or leading geek, I should say) Sheldon, meeting Hawking in a library.

These days Hawking is just as famous in popular culture as the epitome of intelligence as he is as a physicist. This rise to pop-culture icon was fuelled by the phenomenal popularity of Hawking’s popular-science book A Brief History of Time, which has sold more than 10 million copies worldwide since it was first released in 1988. But in recent years, Hawking has also made several appearances on television. In addition to appearing in science shows, he has also starred in Star Trek, as well as several episodes of The Simpsons, the ever-popular animated sitcom.

So here at the Physics WorldHQ, it’s left us speculating as to where Hawking might crop up next. After much agonizing and heated debate, we’ve managed to draw up a shortlist of four popular TV shows. In this week’s Facebook poll we want you to choose the one that you think would make the most entertaining viewing.

In which TV show should Stephen Hawking make his next cameo appearance?

In last week’s poll we addressed the topic of alien life, as we asked you “How common is life in the Milky Way?”.

The question was prompted by recent results from the European Southern Observatory’s High Accuracy Radial velocity Planet Searcher (HARPS) instrument, revealing that our galaxy could be awash with rocky super-Earths orbiting within the habitable zones around faint red stars. The international team of researchers claims that there may be tens of billions of such planets in the Milky Way alone, and probably about 100 in the Sun’s immediate neighbourhood.

62% of respondents chose the option “We are by no means the most intelligent civilization in the galaxy”. 29% opted for “The galaxy is teeming with primitive organisms”, and just 9% believe that “We are alone in the galaxy”.

One voter, Peter Frederick Woolman, wrote “A galaxy teeming with primitive organisms is almost a certainty. I’d find it very surprising if we were the most intelligent civilization in the galaxy, but the existence of intelligence is still far less certain than the existence of primitive organisms.”

Taking a more hard-line stance was Dale Who, a voter who wrote “You’re not even the most intelligent civilisation on the planet”, which also raised some interesting questions about Dale himself.

Thank you for all your participation and we look forward to hearing from you in this week’s poll.

Yesterday’s edition of the Physics World online lecture series saw the cosmologist Lawrence Krauss hold forth on one of his favourite subjects: the life and science of his intellectual hero, Richard Feynman.

Krauss has won awards for his work in science communication, and his biography of Feynman, Quantum Man, garnered Physics World’s own Book of the Year gong for 2011, so it was no surprise to “see” almost 300 of you tuning in yesterday to learn more. But if you weren’t able to watch the lecture live, don’t worry: you can still watch Krauss’s talk on demand here, complete with images of Feynman’s calculus notebooks (a real highlight for me, personally) and Krauss’s eloquent explanation of how Feynman’s beloved first wife, Arline, shaped his way of thinking.

With Feynman as the subject, there were sure to be plenty of questions from audience members at the end of the lecture, and inevitably there wasn’t time for all of them. However, Krauss has now sent us written answers to a few of the most interesting ones, and I’ve pasted his replies below. Enjoy!

Audience member: Do you feel that only scientists like Feynman and Sagan who have an “outgoing” nature that augments the brilliant science they do will be remembered or revered in this day and age?
Lawrence Krauss: Ultimately, I think not. Their names will be most recognized by laypeople in the near term perhaps, but in the long run I believe scientists are remembered for their contributions to changing the way we think about the universe. It takes time for that historical perspective to be obtained, but I believe it arises eventually.

What would you regard as Feynman’s most negative characteristic?
I explain this in more detail in Quantum Man, but I think his persistent desire to redo everything himself (a plus) also meant that he did not follow the work of others as well as he should have. As the American theoretical physicist Sidney Coleman put it, “the other people are not all jerks”, and had Feynman been more aware of this other work, in a number of key areas, he could have had more breakthroughs than he did.

Feynman expressed regret at not reconsidering his involvement with the Manhattan Project after Germany was defeated, but do you think he felt guilt about the technology he helped to create?
I think he ultimately decided he was not responsible for the ills of the world, or what people did with his work. John von Neumann convinced him of this.

Did Feynman believe in any particular physical interpretation of quantum mechanics?
He developed his own, and as for philosophical questions, he avoided them as he got older – rightly, I believe. Amusingly, he said he never really understood quantum mechanics, which is one of the reasons he was hoping for a quantum computer, as that might reveal the quantum world in a way that would have given Feynman a more intuitive understanding.

As with most scientific presentations, it seems as if this one was preaching to the converted. How can we best reach out to a non-scientific audience?
I find it helps to use hooks that relate to things people are already interested in. I used Feynman the “character” as a hook to learn about his science; I used Star Trek as a hook to get people interested in modern physics in my first book; and most recently I have used the religious question of why there is “something rather than nothing” as a hook to teach about modern cosmology.

What area of physics did you talk about when you met Feynman? Also, can we have more details of the weekend you spent with him as an undergraduate?
I was talking about his lecture, which was about the theory of the strong interaction, quantum chromodynamics. I have written about the weekend a bit in the book, and I will leave it at that. My favourite Dirac joke is in the book, too.

Lawrence Krauss’s book Quantum Man: Richard Feynman’s Life in Science (2011 W W Norton) is available now in hardback

A decision on who will build the €1.5bn Square Kilometre Array (SKA) will have to wait after the SKA Organisation announced yesterday that no outcome had been achieved.

SKA is a massive next-generation radio-astronomy facility consisting of around 2000–3000 linked antennas that will probe the first 100 million years after the Big Bang for clues about galaxy evolution, dark matter and dark energy.

Two rival bids are going head-to-head to host the telescope: one led by Australia and the other by South Africa.

The eight members of the SKA Organisation – including China, Italy and the UK – have the final say in who will host the telescope. They met yesterday at Amsterdam’s Schiphol airport in the Netherlands to discuss the site selection advisory committee’s report, which according to leaks suggested that southern Africa had got the nod.

After the meeting the SKA Organisation issued a press release that gave no indication of a site choice, only saying that it “wished to move ahead with the site selection process”.

However, instead of going for a single winner, rumours on the blogs suggest that the SKA Organisation may opt for splitting the SKA antennas between Africa and Australasia. Indeed, this is already happening on a smaller scale via the two SKA prototypes: the Australian Square Kilometre Array Pathfinder in mid-west Australia and the MeerKAT array in the Northern Cape province of South Africa.

Yesterday’s press release alluded that the SKA Organisation may be heading in this direction. The statement says that the members “recognised that it is desirable to maintain an inclusive approach to SKA”, adding that “it is important to maximize the value from the investments made by both candidate host regions”.

The SKA Organisation has now set up a scientific working group to “explore possible implementation options that would achieve this”. The working group will report back to the SKA Organisation at a meeting in mid-May, when perhaps a final decision will be made.

Following my blog last Friday afternoon about the resignation of OPERA spokesperson Antonio Ereditato, it emerged later that evening that OPERA’s physics co-ordinator Dario Autiero, from the Institute of Nuclear Physics in Lyon, France, had also resigned. Nature reported that Autiero felt that tensions within the OPERA collaboration that had always existed were becoming impossible to resolve and that the media attention about superluminal neutrinos added fuel to the fire.

On Saturday, Ereditato broke his silence and wrote a long public statement about his resignation in a letter to the editor of Le Scienze, the Italian edition of Scientific American. In it, he says that words such as “‘errors’, ‘mistakes’ and ‘flop’ were bandied about regarding what in actual fact is standard scientific procedure in experimental work” and that “it is no accident that the word ‘error’ has a completely different meaning in scientific method than it does in common parlance”. He too points towards media attention, saying that “the message [of the results from the first press conference] was excessively sensationalized and portrayed with not always justified simplification” and that the “enormous media interest” put unexpected pressures on the entire collaboration. You can read his entire statement here.

Coincidently or not, the OPERA collaboration held a mini workshop on Friday evening at the Gran Sasso lab that was streamed live online. The “LNGS results on the neutrino velocity topic” workshop included a further analysis of the two errors that led to the superluminal results.

Slides and PDFs of some of the presentations are available online. One of the talks, entitled “Measurements and cross checks on OPERA timing equipments”, was given by G Sirri from INFN Bologna on behalf of the OPERA collaboration. His slides indicate that a connector for a fibre-optic cable that was incorrectly plugged in definitely contributed towards the error. But the cable error alone would have been much larger than the observed error, which perhaps would have led the researchers to find the result implausible. The other error that occurred – a problem with one of OPERA’s oscillators that led to a “time-stamp drift” – caused the neutrino time of flight that was recorded to be longer than the actual travel time. The unfortunate combination of these two “opposing” errors meant that the final result of the neutrinos travelling at a velocity 20 parts per million above the speed of light was an almost believable result. While there has been no official statement from OPERA regarding this just yet, it seems that the mystery of the superluminal neutrinos has been put to rest.